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6CCVD Research

Enhanced Photoluminescence and Electrical Properties of n-Al-Doped ZnO Nanorods/p-B-Doped Diamond Heterojunction

At a Glance

Section titled “At a Glance”
MetadataDetails
Publication Date2022-03-30
JournalInternational Journal of Molecular Sciences
AuthorsYu Yao, Dandan Sang, Liangrui Zou, Dong Zhang, Qingru Wang
InstitutionsChangchun University of Technology, Liaocheng University
Citations11
AnalysisFull AI Review Included

Executive Summary

Section titled “Executive Summary”

The research details the fabrication and characterization of a high-performance n-Aluminum-doped ZnO Nanorods (n-Al:ZnO NRs) / p-Boron-doped Diamond (p-BDD) heterojunction, demonstrating significant improvements over undoped ZnO/BDD devices.

  • Superior Electrical Performance: Al doping drastically improved the device quality, achieving a high rectification ratio of 838 at 5 V (over 40 times the undoped value) and an ultra-low forward turn-on voltage of 0.27 V (compared to 3.4 V for undoped).
  • High Forward Current Density: The forward current reached 67.5 mA at +5 V, which is more than 1300 times higher than the undoped n-ZnO NRs/p-BDD heterojunction.
  • Enhanced Photoluminescence (PL): PL intensity was significantly enhanced, attributed to the combined action of surface plasmon resonance and metal-induced crystallization.
  • Bandgap Engineering: Al doping caused a blue shift in the UV emission peak (to 382 nm) due to the Burstein-Moss effect, widening the ZnO bandgap.
  • WLED Suitability: The device exhibits broadband white light-emitting diode (WLED) emission with chromaticity coordinates (0.2957, 0.2907) close to the standard white light locus.
  • Mechanism Confirmation: Electrical transport analysis confirmed that Al doping reduces the heterojunction barrier height (to 0.55 eV) and increases free carrier concentration, facilitating carrier injection.

Technical Specifications

Section titled “Technical Specifications”
ParameterValueUnitContext
Rectification Ratio (RR)838NoneAt 5 V (n-Al:ZnO/p-BDD)
Turn-on Voltage (Von)0.27Vn-Al:ZnO/p-BDD heterojunction
Forward Current (IF)67.5mAAt +5 V (1300x higher than undoped)
Reverse Leakage Current (IR)0.077”AAt -5 V
Ideality Factor (n)6.8NoneFitted from I-V curve (Undoped n=8.6)
Barrier Height (ΊB)0.55eVn-Al:ZnO/p-BDD heterojunction (Undoped: 0.59 eV)
UV Emission Peak382nmBlue-shifted due to Al doping
CIE Chromaticity Coordinates(0.2957, 0.2907)NoneClose to standard white light
Al:ZnO NR Diameter300nmAverage size
Al:ZnO NR Length1.2”mAverage size
BDD Film Thickness~4”mGrown on Si substrate
BDD Carrier Concentration3.8 x 1017cm-3Extracted from Hall measurements
BDD Breakdown Voltage~107V/cmDiamond substrate property

Key Methodologies

Section titled “Key Methodologies”

The n-Al:ZnO NRs/p-BDD heterojunction was fabricated using a combination of chemical vapor deposition, sputtering, and hydrothermal growth.

  1. BDD Substrate Preparation: p-type BDD films (~4 ”m thick) were grown on silicon (Si) substrates using Hot Filament Chemical Vapor Deposition (HFCVD).
  2. ZnO Seed Layer Deposition: A 30 nm thick ZnO seed crystal layer was deposited onto the BDD film using magnetron sputtering.
  3. Precursor Solution Preparation: A 0.05 M solution was prepared containing zinc acetate dihydrate, aluminum nitrate ninhydrates, and anhydrous ethanol.
  4. Mineralizing Agent Addition: A small amount of solid sodium hydroxide (NaOH) was added to the precursor solution as a mineralizing agent.
  5. Hydrothermal Growth: The BDD substrates with the ZnO seed layer were transferred to an autoclave liner and treated at 150 °C for 24 hours to grow the Al:ZnO NRs.
  6. Cleaning and Drying: The samples were removed from the oven, repeatedly rinsed with anhydrous ethanol solution, and dried at room temperature.
  7. Device Contacting: Silver (Ag) conductors were attached to the conductive BDD surface and Indium Tin Oxide (ITO) glass to form the positive and negative electrodes, respectively, confirming ohmic contact characteristics.

Commercial Applications

Section titled “Commercial Applications”

This high-performance, diamond-based heterojunction technology is highly relevant for applications requiring stability, high power handling, and efficient light emission.

  • High-Temperature Optoelectronics: The thermal stability of BDD (compatible with processing above 400 °C) makes the device ideal for functional components operating in harsh, high-temperature environments.
  • Advanced White Light-Emitting Diodes (WLEDs): The enhanced PL intensity and optimized CIE coordinates (0.2957, 0.2907) support the development of novel, high-performance WLEDs.
  • High-Power Switching and Rectification: The high rectification ratio (838) and extremely low turn-on voltage (0.27 V) are critical for reducing power losses and improving the efficiency of rectifier diodes and switching devices.
  • UV Photodetectors and Emitters: The strong UV emission peak (382 nm) and wide bandgap materials are suitable for deep UV sensing and light source applications.
  • High-Frequency/High-Power RF Devices: Utilizing the inherent properties of BDD, including high breakdown voltage and high electron hole mobility, for durable electronics in demanding radio frequency (RF) systems.
View Original Abstract

The hydrothermal approach has been used to fabricate a heterojunction of n-aluminum-doped ZnO nanorods/p-B-doped diamond (n-Al:ZnO NRs/p-BDD). It exhibits a significant increase in photoluminescence (PL) intensity and a blue shift of the UV emission peak when compared to the n-ZnO NRs/p-BDD heterojunction. The current voltage (I-V) characteristics exhibit excellent rectifying behavior with a high rectification ratio of 838 at 5 V. The n-Al:ZnO NRs/p-BDD heterojunction shows a minimum turn-on voltage (0.27 V) and reverse leakage current (0.077 ÎŒA). The forward current of the n-Al:ZnO NRs/p-BDD heterojunction is more than 1300 times than that of the n-ZnO NRs/p-BDD heterojunction at 5 V. The ideality factor and the barrier height of the Al-doped device were found to decrease. The electrical transport behavior and carrier injection process of the n-Al:ZnO NRs/p-BDD heterojunction were analyzed through the equilibrium energy band diagrams and semiconductor theoretical models.

Tech Support

Section titled “Tech Support”

Original Source

Section titled “Original Source”

References

Section titled “References”
  1. 2005 - A comprehensive review of ZnO materials and devices [Crossref]
  2. 2001 - Room-Temperature Ultraviolet Nanowire Nanolasers [Crossref]
  3. 2002 - Controlled growth of ZnO nanowires and their optical properties [Crossref]
  4. 2021 - Room temperature ferromagnetism and enhanced photocatalytic activity of ZnO:Ga nanorods [Crossref]
  5. 2021 - Enhanced photoelectrochemical performance of vertically aligned ZnO nanowires [Crossref]
  6. 2021 - A novel self-supported porous ZnO nanobelt arrays on Zn foils: Excellent binder-free anode materials for LIBs [Crossref]
  7. 2021 - Enhanced UV photodetectivity in solution driven ZnO nanosheets via piezo-phototronic effect [Crossref]
  8. 2015 - n-ZnO/p-4H-SiC diode: Structural, electrical, and photoresponse characteristics [Crossref]
  9. 2020 - Enhanced Piezoresistive Behavior of SiC Nanowire by Coupling with Piezoelectric Effect [Crossref]
  10. 2021 - High performance NiO/Ag/NiO transparent conducting electrodes for p-Si/ n-ZnO heterojunction photodiodes [Crossref]

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